Dipole moment is a measure of the polarity of a bond. It is defined as the product of the charge and the distance between the charges. In a covalent bond, the electrons are shared between the two atoms. If the electrons are shared equally, the bond is nonpolar. If the electrons are shared unequally, the bond is polar. The electronegativity of an atom is a measure of its ability to attract electrons. The greater the electronegativity difference between two atoms, the more polar the bond will be.

Of the five bonds listed, H-H is the only one that is nonpolar. This is because hydrogen has a very low electronegativity. The other four bonds are all polar, with the electronegative atom having a partial negative charge and the electropositive atom having a partial positive charge.